Rising wastewater operating costs are main driver of water tariff growth in 2018October 31, 2018 (www.waternewswire.com) The average tariff for wastewater services grew by 4.1% between July 2017 and July 2018, compared with a 3.5% increase for the average water tariff in the same period, according to new data from released by Global Water Intelligence, as part of its 2018 Global Water Tariff Survey.